Machine gun



March 2, 1943. w. A. PLOURDE 2,312,586

MACHINE GUN Filed Jan. 8,1941

2 Y IU/AZ/AM ,4. fixer/A05 ATT RNEYS Patented Mar. 2, 1943 MACHINE GUN William A. Plourde. Kenmore, N. Y., assignor to Bell Aircraft Corporation, Buffalo, N. Y.

Application January 8, 1941, Serial No. 373,636

4 Claims.

This invention relates to machine guns, and more particularly to improvements in machine guns for use in relatively constricted places such as when mounted in modern combat airplanes, tanks, and the like.

A standard method of mounting a machine gun upon combat airplanes, for example, involves the fixing of the gun so as to be substantially enclosed within the airplane fuselage or nacelle shell with its muzzle extending forwardly therethrough and its butt end disposed within convenient reach of the pilot-gunner. This brings the rear end of the gun into the region of the instrument panel of the pilot cockpit and into close association with adjacent fuselage and cockpit cover structural elements. To permit ready access to the interiors thereof, machine guns of the presently used types are usually provided with detachable back plates at the rear ends thereof; and the back plates are arranged to be fastened to the corresponding gun casings in substantial manner so as to successfully withstand the recoil forces of the firing operation which are transmitted to the back plates through the recoil buffer parts.

For this purpose the back plate is usually fixed to the gun casing by a connection device embodying a transverse slide lock principle; but the arrangements of the prior art invariably require the provision of an open space of substantial size immediately above or to one side of the back plate to permit of its disengagement by a sliding movement equal in extent to the corresponding vertical or lateral dimension of the back plate. Consequently, the airplane structure immediately above or to the side of the back plate must be disposed at an undesirably increased elevation or other position of spaced relation with respect to the gun butt for no other useful purposes; and fuselage frontal area and/or pilot-visibility and/or other airplane design factors are thereby adversely affected.

One of the objects of the present invention is to avoid the objections and disadvantages of the prior art set forth hereinabove. Another object of the invention is to provide an improved machine gun which is adapted to be serviced in an improved manner subsequent to installation in a combat airplane or the like. Another object of the invention is to provide an improved machine gun which is adapted to be mounted within constricted spaces in airplane structures, or the like, in an improved manner whereby the airplane or other mounting structure may more out inclusion of otherwise waste spaces for accommodating detaching movements of certain gun parts in connection with the servicing thereof. Another object of the invention is to provide a machine gun embodying an improved form of back plate mounting connection whereby the back plate may be removed for servicing of the gun in accord with an improved and simplified procedure. Other objects and advantages of the invention will appear from the specification hereinafter.

In the drawing:

Fig. 1 is a fragmentary perspective of a'gun of the invention shown in association with typical adjacent structure of a mounting airplane, or the like, with the back plate portion of the gun shown in disassembled relation therefrom; and

Fig. 2 is a rear elevation of the gun and typical adjacent airplane structure.

The drawing illustrates the invention in conjunction with a machine gun in which may be otherwise of any type furnished by manufacturers thereof, but it is fitted with a back plate I2 bymeans of an improved detachable connection arrangement, as will be explained hereinafter. Typical framing elements [4 of a mounting airplane cockpit structure are shown adjacent the butt end of the gun; and in Fig. 2 additional adjacent airplane structure such as the pilot instrument panel I6 is illustrated. The gun I0 is shown as being provided with the usual operating slide grip device l8 and a back plate lock release latch 20, as are customarily furnished as integral parts of presently standard type machine guns; and it will be undertsood that the illustration of the gun Ill of the drawing is intended to be simply indicative of any suitable type of machine gun as maybe selected for mounting upon the airplane. Also, it will be understood that the airplane structural framing members and instrument board of the drawing are intended only to be indicative of typical corresponding structural elements normally located in the region of a fixed type machine gun when mounted upon the fuselage of a single seater combat airplane, and that many other forms of structural elements may exist in the region thereof in any given case of machine gun mounting.

The gun I0 is shown as including a casing 22 which is open at its rear end to provide access to the internal working parts of the gun' for servicing thereof. To mount the back plate [2 nearly conform to an ideal arrangement withupon the casing 22, the opposite side wall portions of the casing are extended rearwardly as at 24,

and each extending wall portion is interiorly grooved as at 26 to provide vertical recesses in which corresponding side edge portions of the back plate 12 are arranged to be slidably fitted. The overhanging outer edge portions of the casing wall extensions 24 are cut away in line with the corresponding recesses at regularly spaced intervals so as to provide spaced fingers 21 divided by ways 28 extending rearwardly through the recesses 26. The recess-engaging side edge portions of the back plate l2 are also cut away as at 30 at regularl spaced intervals in such manner as to provide on the back plate l2 vertically spaced and laterally extending ears 32 (Fig. 1')

which are adapted to register with and to move 'fbeing'freely accommodated byLthe ways 28xduring movement of the ears 32 into the .plane of the casingrecesses 26. The back. plate may then be dropped as also indicated 'by :the vertical arrow of Fig. 1 into operative position, whereupon the ears 32 of the back plate will .be firmly "engaged behind corresponding fingers 2-! of the casing end walls. As is customary, the latching lever 29 is pivotally mounted upon the backiplate I 2 and is arranged to be spring-pressed so as to move into back plate locking position relative to the gun casing 22 upon arrival of the back plate intooperative position as explained hereinabove, and untilsuch time asit maybe released .by manual manipulation preliminary .to disassembly of'the back plate fromzthe gun.

To disassemble the back "plate from the gun casing the latch 20 is manually "lifted-to release the locking connection between the back ;plate and the gun casing. Further upward pressure against the bottom-of the .back'platethen causes the latter to slide upwardly until the ears 32 clear the fingers 21 whereupon it is freed to'be drawn rearwardly out of engagement with the gun casing. Thus, it will benoted that the operations of attaching and detaching the back plate from the gun casing require vertical movements of the back plate relative tothe gun-casi-ngonly until the corresponding ears '32 clear the fingers 21, and it will be noted that this required move- .ment is only a fraction of the total vertical .di-

mension of the back plate l2. -Consequently, in designing the airplane or other gun mounting structure the structural framing elements corresponding to the members M of the drawing may be disposed relatively close to the-gun casing in the region of the back plate without interference with assembly or disassembly 'of the back plate relative to the gun casing during gun servicing operations subsequent to mounting of'the gun upon the airplane.

Thus, an improved combination gun and supporting framing structure is provided-which more nearly conforms to an ideally compact gun and gun mounting structure and which involves substantially less space forpermitting the gun back plate to be moved transversely of the gun casing for disassembly'of the back plate in order to provide access to the interior of the gun than in the case of theprior art. It'will be understood that the form and number andrelative arrangement and proportioning of the ear and finger portions -32 and 21, respectively, of the back plate and gun casing members may be varied as required in any given instance to provide the desired strength and back plate assembly and disassembly operation. It will also be understood that although only one form of the invention has been shown and described in detail, it will be apparent to those skilled in the art that the invention is not so limited but that various changes may be made therein without departing from' the spirit of the invention or the scope of the appended claims.

I claim:

1. In a machine gun, an open end gun casing, .a back plate slidably mounted upon said casing at the open end portion thereof by means of a slide connection means permitting movement of said back plate in a direction transversely of the longitudinal axis of said gun, said means comprising opposed series of spaced finger devices aligned parallel to the direction of sliding movement and extending from adjacent portions of said back plate and said casing, said finger devices being adapted to interlock in one position of sliding adjustment of said back plate relative to said casing and to disengage upon transverse sliding movement of said back plate to an extent approximately equal to one-half the pitch of spacingof said finger devices.

2. In a machine gun, a gun casing having an open rear end,"closure means therefor having opposite parallel marginal portions, said, gun casing having corresponding opposite parallel marginal portions adjacent said open rear end, inwardly directed flanges on the marginal portions of said casing and outwardly directed flanges on the marginal portions of said closure means, the flanges of 'both the casing and the closure means comprising a series of relatively short flanges having spaces therebetween of approximately the lengths of the flanges, whereby the closure means may be assembled by placing it against the open rear end of the gun casing with the flanges of the .closure means and those of the casing out of registry,-and subsequently moving the closure means in the direction of extent of the flanges a distance approximating the length'of one short flange to dispose the flanges of the casing and the flanges of the closure means in interlocking relation.

3. In a machine gun, a gun-casing having an open rear end, closure means therefor having 0pposite parallel marginal portions, said gun casing having corresponding opposite parallel marginal portions adjacent said open rear end, inwardly directed flanges on the marginal portions of said casing and outwardly directed flanges on the marginal portions of said closure means, the flanges of both the casing vandthe closure means comprising a series of relatively short flanges having spaces therebetween of approximately the lengths of the flanges, whereby the closure means may be assembled by placing it against the open rear end of the gun casing with the flanges of the closure means and those of the casing out of registry, and subsequently moving the closure means in the direction of extent of the flanges a distance approximating the length of one short flange to dispose the flanges of the casing and .t'heflanges of the closure means in interlocking relation, and stop means for limiting movement ofsaid closure means at casing-closing position.

4. In a. machine gun, a gun casing having an open rear end, closure means therefor having opposite parallel margin-a1 portions, said gun casing having corresponding opposite parallel marginal portions adjacent said open rear end, inwardly directed flanges on the marginal portions of said casing and outwardly directed flanges on the marginal portions of said closure means, the flanges of both the casing and the closure means comprising a series of relatively short flanges having spaces therebetween greater than the lengths of the flanges, whereby the closure means may be assembled by placing it against the open rear end of the gun casing with the flanges of the closure means and those of the casing out of registry, and. subsequently moving the closure means in the direction of extent of the flanges a distance approximating the length of one short flange to dispose the flanges of the casing and the flanges of the closure means in interlocking relation.

WILLIAM A. PLOURDE. 

